Doctor-Reviewed Health Guides: Conditions, Procedures & Health News

The anion gap is a value calculated from routine electrolyte results that shows whether the blood's acid-base balance is normal. Labs work it out from your sodium, chloride and CO2 (bicarbonate) levels. Providers use it to spot metabolic acidosis, when the blood has more acid than normal. There's no universal normal range, so your lab's own range applies.

The Epworth Sleepiness Scale (ESS) is a short self-assessment that measures how likely you are to doze off during the day. You rate eight everyday situations from 0 to 3, for a total of 0 to 24. A score of 0 to 10 is normal, while 11 or higher suggests excessive daytime sleepiness that may need more testing.

Breast cancer screening is testing that finds breast cancer early, before symptoms, when it's easiest to treat. Women at average risk should have their first screening at age 40 and repeat it every one to two years. A mammogram is the best first test for most women. If you're at high risk, your provider may start before 40.

A stool test checks a sample of your poop for germs (bacteria, viruses and parasites), hidden blood and signs of digestive disease. Providers use it to find what's causing symptoms such as diarrhea, belly pain or blood in your stool, and to help detect colon cancer. You collect the sample at home, and results take one to three days.

Blood tests for cancer are one of many tools providers use to diagnose, assess and manage cancer, but blood work alone can't detect most types of cancer. It can help detect some blood cancers, such as leukemia, lymphoma and multiple myeloma. To confirm cancer, you'll almost always need more tests, such as a biopsy or imaging.

A breast ultrasound is an imaging test that uses sound waves to take pictures of the inside of the breast. It can show whether a lump is a fluid-filled cyst, which is usually not cancer, or a solid mass that may need more testing. It takes about half an hour, uses no radiation and has no known risks.

A myelogram is an imaging test that uses contrast material with X-rays or a CT scan to show the spinal canal, spinal cord, nerves and the disks and bones around them. The contrast is injected into the fluid around the spinal cord. It's usually done when a CT scan or MRI has not explained back pain or nerve symptoms.

A functional MRI (fMRI) uses an MRI machine to track blood flow in the brain while you do simple tasks, such as tapping your fingers. Areas that are working harder use more oxygen and show up brighter. Its main use is to map important brain areas before surgery or radiation so they can be protected.

Swan-Ganz catheterization places a thin tube, also called a pulmonary artery catheter, through a large vein and the right side of the heart into the pulmonary artery. It lets the care team measure pressures inside the heart and lungs and estimate how much blood the heart pumps. Serious complications happen in about 1% of procedures in experienced centers.

A PCR (polymerase chain reaction) test is a lab technique that makes many copies of a tiny amount of genetic material (DNA or RNA) so it can be detected and studied. Providers use PCR to diagnose infections such as COVID-19 and the flu, find gene changes in tumors and diagnose genetic diseases. Swab results usually take about a day.

A urine protein creatinine ratio (UPCR) test measures protein and creatinine in a single urine sample. Protein in urine can be a sign of kidney damage, and creatinine is a marker providers use to adjust the protein reading. It is quick, painless and has no risks.

The NIH Stroke Scale (NIHSS) is a quick test of stroke severity. A provider checks your awareness, consciousness, coordination, language and speech, movement and senses in about 15 parts, then adds up the points. Scores run from 0 to 42, and it takes less than 10 minutes and does not hurt.

A MELD (Model for End-Stage Liver Disease) score is a number, usually between 6 and 40, that shows how sick you are with liver disease and how soon you may need a liver transplant. A higher score means more severe disease.

The Bishop score is a tool used to check how ready the cervix is for labor. Scores range from 0 to 13. A score of 8 or more means an induction is likely to lead to a vaginal birth. A score of 5 or less means your body isn't ready yet. It's an estimate, not a guarantee.

A nonstress test (NST) is a safe, painless pregnancy test that measures the baby's heart rate and how it responds to movement. It's usually done after 28 weeks. A reactive result means the heart rate rose with movement at least twice in 20 minutes. A nonreactive result means more testing may be needed.

The Beighton score is a painless exam that measures how flexible the joints are, using a 9-point scale. A provider checks the thumbs, fingers, elbows, knees and spine. A score of 4 or more, with pain in 4 or more joints for at least 3 months, suggests joint hypermobility syndrome. It can't diagnose conditions like Ehlers-Danlos syndrome on its own.

A pulse volume recording, or PVR test, is a painless test that measures blood pressure and blood flow in the legs using blood pressure cuffs and an ultrasound device. It's used to diagnose or monitor peripheral artery disease (PAD) and find the area of a narrowed or blocked artery. It takes 30 to 60 minutes.

An ankle-brachial index (ABI) is a painless test that compares blood pressure in the ankles and arms to check for peripheral artery disease (PAD), a buildup of plaque in the leg arteries. A normal ABI is 1.0 to 1.3, and 0.9 or lower means you have PAD. It has no needles and takes 10 to 20 minutes.

Thyroid tests (thyroid function tests) check how well your thyroid gland works. They fall into two groups: blood tests that measure thyroid hormones and antibodies, such as TSH, T4 and T3, and imaging or nuclear medicine scans that show your thyroid's size, shape and function. Together they help diagnose hypothyroidism, hyperthyroidism, Graves' disease, Hashimoto's disease and thyroid cancer.

A breast biopsy is a procedure where a provider removes a sample of breast tissue, with a needle or surgery, to check it for cancer. It's the only way to rule breast cancer in or out after a lump or an abnormal imaging result. Most biopsies don't find cancer: 80% of people who have one don't have breast cancer.

Genetic testing for cancer risk checks your DNA, usually from a blood or saliva sample, for inherited gene changes that raise your chance of certain cancers, such as changes in the BRCA genes. About 5% to 10% of cancers involve an inherited mutation. A positive result means higher risk, not that you have or will get cancer.

The glucose test in pregnancy checks for gestational diabetes, a condition where blood sugar is too high during pregnancy. It usually happens between weeks 24 and 28. You drink a sugary liquid, then have blood drawn from a vein in your arm.

A heart rate monitor is a device that shows how fast or slow your heart beats in real time, in beats per minute (bpm). Most are wearable, such as watches, arm bands and rings, and many save your data so you can review it later or share it with your provider.

A carotid ultrasound (carotid duplex) is a painless test that uses sound waves to make pictures of the two carotid arteries in the neck, which carry blood to the brain. It looks for plaque, blood clots and narrowing that can raise the risk of stroke. The test takes 30 to 45 minutes, needs no preparation and uses no radiation.